Elastic spring



Jan. 19, 1937. E. H. PIRON ELASTIC SPRING Filed May 27. 1935 INVENTOR. 2721/7 1 ATTORNEY.

Patented Jan. 19, 1937 UNITED STATES ELASTIC SPRING Emil H. Piron, New York, N. Y., assignor, mesne assignments, to Transit Research by Corporation, New York, N. Y., a corporation of New York Application May 21, 19:5, Serial No. 23,651

22 Claims. (01. car-es) This invention relates to springs of the type wherein concentric load imposing and load receiving members impose shear loading on an elastic medium such as rubber therebetween, such as is described in my co-pending application Serial Number 23,046, filed May 23, 1935.

The object of this invention is to provide a spring which uses all of the rubber'to best advantage, which, in preferred form, is subjected to uniform stress within any cylinder, varying stress from one cylinder to the next with provision for taking the cylinders out of further deflecting action upon reaching their maximum strain while permitting the remaining cylinders to continue deflection until each cylinder has been subjected to the maximum strain of which it is capable. In this way the rubber is used to its maximum ability without overstressing or overstraining in any cylinder.

Another object is to teach the manner of altering the typical load deflection curve of the shear spring to obtain softness under light loads and increasing stillness under increasing loads as may be desired for a wide variety of service conditions.

Another object is to teach a slight variation in construction which will improve the stability thereof in other than axial directions without materially altering the desired characteristics.

Another object is to provide means for correcting the characteristics of the spring if desired or as a result of the permanent set which the elastic material will take after a period of operation.

Other objects and advantages will become hereinafter more fully apparent as reference is had to the accompanying drawing wherein my invention is illustrated by way of example and in which;

Figure 1 is a longitudinal section through my improved spring,

Figure 2' is a top plan view with the stop plate removed,

Figure 3 is a bottom plan view of the stop plate showing the steps, v

Figure 4 is a modified form of the spring of Figure 1.

Figure 5 is a longitudinal section through a modified form of stop plate, and

Figures 6, '7 and 8 are longitudinal sections through metallic cylinders showing several types of adjusting means. I

Figure 9 is a longitudinal radial section taken along the line 99 of Figure 2.

Referring first to Figure 1, l designates a shaft of metal or its equivalent which is, wrapped with a plurality of alternate concentric cylinders of rubber herein illustrated as being four in number 2, 2a, 2b, 2c and metal 3, 3a, 3b, 3c and-3d, all of which are concentric with an outer cylinder 4 having a flange retaining means 1! integral therewith. The rubber cylinders are'of.- progressively decreasing height with respect to each other from the inside to the outside and the height or axial length of the inside surface of each is greater than the height of axial length 'of its outside surface.

The height of any element 2, 2a, 2b, 2c, is inversely proportional to the diameter at which it is taken, or approximately so, so that the shear area of that element is practically constant. However, in order that the deflection of the element 2 reach its permissible maximum under a lower load than does element 2a, the area of the inside surface'of the cylinder 2a must be greater than the area of the outside surface of the cylinder 2. This is equivalent to saying that the height of the contact of rubber 2a with the metal cylinder 3a must be greater than the contact of rubber 2 with the same metal cylinder. This gives a design as'shown for instance by the partially dotted line ab, with a space between the line ab and the inner surface of the cylinder 3a. 'In order to increase the stability of the spring in a radial direction, the space between ab and the inner surface of 3a is filled with elastic material. I have found that the quantity of elastic material thus added is very small and changes but little the resistance of the spring to deflection in an axial direction although it increases very much the radial stiffness. The same conditions as above are realized for the other elements 2a, 2b, 2c.

The quality of the elastic material may be changed from element to element according to particular conditions. For instance, if it is desired that the height of the outer elements be greater than required to satisfy the above rules of design applied to an elastic material having a given modulus of elasticity, then an elastic material having a smaller modulus of elasticity may be used for the outer elements. Theoretically the modulus of elasticity of each-cylinder of rubber can be varied from its inner to its outer surface but actually the results of efforts to accomplish this are unsatisfactory and when the results of the spring as a whole are taken, it is found that this is entirely unnecessary because, for all prac tical considerations, the same results are obtained as if this were actually done.

In order to manufacture this spring properly and economically, the cylinders of rubber are made in segments or half cylinders and molded or otherwise surfacebonded to metallic segments 55 of similar surface areas. Actually, the metallic segments when placed in abutting relation for assembly about the member I are less than 360 in circumference so that upon compression of the rubber for insertion into the cylinder 4 the edges of the metal do not actually contact for this would prevent uniform compression from cylinder to cylinder. The faces of the rubber segments are provided with projections 20, as illustrated in Figure 9 and more fully explained in my copending application Serial Number 23,046 previously referred to. The upper and lower edges of each metallic segment except 3 are flanged as indicated by the numerals 6 and I, theflanges 6 serving as abutments for contact by the plate 8 secured to the shaft I. The flanges 6 also constitute one part of an adjustment means for altering the characteristics of the spring or for correcting for the set of the elastic material after a period of usage. The other part of the adjustment means may be a threaded cap 9 where the flange is threaded as at ID as indicated in Figure 6, ora fitted shim [2 as shown in Figure 7, or a plain shim l3 as shown in-Figure 8. The adjustment means of Figure 5 is carried by the stop member 8a, in which each step is individually adjustable by means ofthe screws I I. A central adjustment means I2 is provided at the center for altering the position of the plate 8a with respect to the main member la and the flanges 6. In Figure 1 this central adjustment is affected by shims l3.

The plate 8 is provided with stepped stops-l4, a, Mb, c, for progressively contacting the flanges 6. Sincethe rubber 2 is under the greatest unit loading the step II will contact the flange of the cylinder 3a and thereafter the step a will contact the flange of the cylinder 3?), and so on sothat the rubber cylinders are taken out ofaction progressively from the inner to the outer thereof. r

' The design lends itself to adaptation to'a given set of figures and the number of load deflection curves which can be obtained therewith is pracrelative areas, etc.

The spring of Figure 4 is very similar to that previouslyexplained but differs therefrom in that the metallic projections l5, l6, and II are formed 1 h f fthat the lower rather thant eupper sur aceo eyflat and; inclined r 8 dip This construction has certain advantages from manufacturing standpoint as the mold S plate fixedly secured to the inner of said members less complicated and productionmore rapid.

In both instances tool holes l8 are providedin the cup or flange 5 so that the outer split metallic 1; In a spring, concentric load imposing and load receiving members having alternate concentric cylinders of metal and rubber therebetween, said cylinders of elastic material each having a height at any concentric section substantially in-' versely with the radius of that section, and stop means for progressively contacting said metallic,

, cylinders from the inside radially outwardly of s d i s-f -2. In a spring, concentric load imposing and load receiving members having alternate concentriccylinders of metal and rubber therebetween,

whereby the shear area is substantially constant within any cylinder, said elastic cylinders increasing in shear area from one cylinder to the next radially outwardly of the spring, and stop means adapted to progressively contact said metallic cylinders upon the imposition of shear loads to said spring.

3. In a spring, concentric load imposing and load receiving members having alternate concentric cylinders of metal and rubber therebetween, said cylinders of elastic material each varying in height substantially inversely with the radius, whereby the shear area is substantially constant within any cylinder, said elastic cylinders increasing in shear area from one cylinder to the next radially outwardly of the spring, and stop means adapted to progressively contact said metallic cylinders from the inner to the outer thereof upo imposition of shear loads to said spring.

4. In a spring, concentric load imposing and load receiving members having alternate concentric cylinders of metal and elastic material therebetween, said elastic cylinders each having a substantially constant shear area, said elastic cylinders varying in 'shear area from one cylinder to the next radially outwardly thereof whereby the stress under a given load decreases from one cylinder to the next, and means-for limiting the possible deflection of each of said cylinders to its predetermined maximum.

5. In a spring, concentric load imposing and load-receiving members having alternate concentric cylinders of rubber and metal therebetween, said rubber cylinders varying in shear-area from one cylinder to the next radially outwardly of the spring, and a stop means for progressively con tacting said metal cylinders from the inner to the outer thereof to alter the "load deflection curve of said spring.

6. In a spring, concentric load and 40 load receiving members having ,altemate concentric cylinders of rubberjand metal therebetween, said cylinders of rubber each having substantially flatsimilarly-inclined surfaces, and a plate member. having steps for progressively contacting the exposed edges of said metallic cylinders upon imposition of shear loading on the spring.

7; In a} spring, concentric load imposing and load receiving members having alternate concentric cylinders of ,rubberand metal therebetween,

said cylindersof rubber each substantially ferent angles with the axis of said members, and a having steps integral therewith for contacting said metallic cylinders progressively from the inside to the outer thereof. v V v 8. The combination as set forth in claim 7 characterized in that each of said metallic cylinders has a flange integral with the upper edge thereof for contact with said steps.

9. The combination as set forth in claim 7 characterized inthat each of said metallic cylinders has a flange integral with the upper edge thereof for contact bysaid steps, and individual means for adjusting the relative position of said steps and said metallic cylinders whereby the characteristics of the spring may bealtered or corrected.

10. The combination asset forth in claim 7 characterized in that each of said-metallic cylinders has a flange integral with the upper edge thereof for-contact by said steps, and means individual to each of said flanges for altering the eflective height thereof whereby the amount of deflection by said rubber cylinders before contact with said steps may be altered at will.

11. In a spring, concentric load imposing and load receiving members having alternate concentric cylinders of metal andrubber therebetween, the innermost one of said metallic cylinders being of metal and closely encircling the inner one of said members, a plate having stop means integral therewith for progressively contacting said me tallic cylinders to limit the maximum possibledeflection by each of said rubber cylinders, and

means for adjustingsaid plate on said inner member with respect to the adjacent edge of said innermost metallic cylinder to adjust the amount of deflection before contact of said stops with said cylinders. v

12. The combination as set forth in claim 11 together with means for adjusting the individual distances between each metallic cylinder and its own stop.

13. In a ,spring, concentric load imposing and load receiving members having alternate concentric cylinders ofmetal and rubber therebetween, the top of the springbeing generally coni-' cal, the innermost one of said concentric cylinders being of metal and closely fitting the inner of said members, and a plate fixed to the inner 01' said members carrying concentric stepped portions for contact with the tops of said metal cylinders, said plate having a hollowed out portion at its center for receiving the upper end of said innermost metallic cylinder and constituting means for preventing axial displacement of said spring on said inner member.

14. The combination as set forth in claim 13 5 together with means for altering the volume of said hollowed out portion for adjustment of said plate with respect to said spring.

15. In a spring, concentric load load receiving members having alternate concentric cylinders of metal and rubber therebetween, the top and bottom surfaces of all of said cylinders forming composite surfaces of generally conical shape, having similar inclination with the axis thereof, each of said cylinders of rubber having a substantially constant shear surface within itself with the outer shear surface of each thereof being less than the area'of the encircling metallic cylinder, and means for bracing each of said cylinders to lend stability to the spring in other than axial directions.

16. In a spring, concentric load imposing and load receiving members having alternate concentric cylinders of rubber and metal therebetween, the inner and outer shear surfaces of each of said metallic cylinders being of substantially equal area, the outer shear surface of each of said rubber cylinders covering less than the total surface of the surrounding metallic surface, and a.

rubber filler covering the exposed portion of each 'of said cylinders and extending into integral contact with the encircled rubber to lend stability thereto.

17. In a spring, concentric load imposing and load receiving members, assembled segments coniimposing and members, the total circumferential extent of each of the cylinders of metal being less than a complete circle whereby the abutting edges of each segment thereof are in slightly spaced relation with the adjacent edges upon assembly, the total circumferential extent of each of said cylinders of rubber being slightly greater than a complete circle whereby upon assembly into circular form radial pressure must be. interposed on said segments, the outer of said members being cylindrical and adapted to maintain radial compression on said cylinders upon assembly therein, the abutting faces of said rubber segments having reduced areas whereby said' faces do not become pinched between said metallic edges upon imposition of the radial pressures, and a plate fixedly secured to the inner of said members adjacent the top of saidspring, said plate having concentric steps adapted to progressively contact the metallic cylinders for limiting the total possible stresses to which any cylinder may be subjected, each of said metallic cylinders having flanged top portions for contact by its step.

18. The combination as set forth in claim 17 together with means for adjusting said plate with respect to said metallic cylinders.

19. The combination as set forth in claim 17 together with means to adjust said top plate with the remainder thereof.

21. In combination, an elastic spring comprising inner and outer stiff cylindrical members having at least one intermediate stiff cylindrical member therebetween, elastic cylinders between said members adapted to resist relative movement between said members in resilient shear,

'one of said elastic cylinders being adapted to deflect at a greater rate than the remainder thereof, and means for limiting the total possible deflection of said one elastic cylinder while permitting continued deflection of the remainder thereof.

22. In a spring, inner and outer concentric stiif cylindrical members having atleast one concentric stiif cylindrical member radially therebetween, elastic cylinders separating said cylindrical members, and stop means carried by said inner member for contact with at least one of the intermediate stiff members for limiting the possible deflection of the inner of said elastic cylinders.

while permitting further deflection of the remainder of said elastic cylinders.

- EMIL H. PIRON. 

